Longer incubation in primary antibody - (Oct/30/2010 )

Hi!
I incubated my blots in primary antibody for more than 24 hrs in 2.5% Milk at 4 degree.
One of my primary is notorious for non specific binding while the others are pretty neat.
Will longer incubation in primary give me a lot of nonspecific binding and background?
Any suggestion will be highly appreciated.